The objective of this project is to assess the feasibility of investigating the effect of silymarin, derived from the milk thistle plant, Silybum marianum (L.) Gaertn. in preventing or reversing the complications of chronic infection with hepatitis C virus (HCV) in patients with human immunodeficiency virus (HIV), to serve as the basis of a more definitive study. Allopathic therapeutic interventions for HCV are expensive and poorly tolerated, particularly with the genotype most commonly encountered in the US. There are limited rigorous assessments of the dietary supplement milk thistle, but there is suggestion of benefit and much interest on the part of co-infected patients and their providers. Specific aims: 1) To collect preliminary information on the safety and tolerability of milk thistle in HCV and HIV co-infected patients who are not on highly active antiretroviral therapy (HAART). 2)To collect preliminary information on the safety and tolerability of milk thistle in HCV and HIV co-infected patients who are on highly active antiretroviral therapy (HAART). 3) To collect preliminary information on the efficacy of milk thistle in HCV and HIV co-infected patients in preparation for a larger, more definitive trial. Co-infected patients will be randomly assigned to receive silymarin or a similar appearing placebo. Participants will be recruited from a large cohort of HCV-infected individuals currently enrolled in a large inner-city AIDS center. Participants will receive the study treatment daily for 52 weeks. Measures to be assessed will include: retention in the study, compliance with study assignment, self-described symptoms, liver enzyme levels, viral load and clearance, and quality of life (SF36 survey), and liver biopsy when available. It is hypothesized that silymarin can prevent progression of liver disease and possibly reverse hepatic lesions that are already present, as well as improve the quality of life. This exploratory project is anticipated to provide data to plan larger and more definitive studies of the effect of milk thistle on HCV infection. Evidence of beneficial effect of an inexpensive and benign herbal dietary supplement would have great impact on the large population suffering from chronic HCV. [unreadable] [unreadable]